from collections import defaultdict

class Attributes :
    Domains = defaultdict(list)
    def __init__(self, attribute = "", value = "") :
        if value not in self.Domains[attribute] :
            self.Domains[attribute].append(value)
        self.__value = value

    def GetValue(self) :
        return self.__value


class Buying(Attributes) :
    def __init__(self, value = "") :
        Attributes.__init__(self, "buying", value)

class Maint(Attributes) :
    def __init__(self, value = "") :
        Attributes.__init__(self, "maint", value)

class Doors(Attributes) :
    def __init__(self, value = "") :
        Attributes.__init__(self, "doors", value)

class Persons(Attributes) :
    def __init__(self, value = "") :
        Attributes.__init__(self, "persons", value)

class LugBoot(Attributes) :
    def __init__(self, value = "") :
        Attributes.__init__(self, "lug_boot", value)

class Safety(Attributes) :
    def __init__(self, value = "") :
        Attributes.__init__(self, "safety", value)

class Attractiveness(Attributes) :
    def __init__(self, value = "") :
        Attributes.__init__(self, "attractiveness", value)